In the field of semiconductor resists, with developing very large scale integrated circuits, higher minute processing techniques have been demanded. Thereupon, light sources of shorter wavelength beams such as KrF excimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm) and F2 excimer laser (wavelength: 157 nm) are utilized instead of g-ray (wavelength: 436 nm) or i-ray (wavelength: 365 nm) of a conventional high-pressure mercury lamp.
Moreover, with rises in the integration level of semiconductor integrated circuits, there has been also demanded for resists with better resolution (formation of patterns in submicron order, quartermicron order or smaller) and for improvement of etching resistance in the process of dry development.
However, even when KrF excimer laser or ArF excimer laser is applied to a conventional resist material (such as a novolak resin/diazonaphthoquinone-based positive resist) in which g-ray or i-ray is employed, sensitivity and resolution of the conventional resist materials are considerably deteriorated owing to light absorption by the novolak resin.
Sondi and Matijevic disclose a film composed of a p-hydroxystyrene-t-butyl acrylate copolymer containing SiO2 nanoparticles (silicasol) as a resist having applicability to an exposure light source of shorter wavelength beams (I. Sondi and E. Matijevic, Resist Technology and Processing XVII, Francis M. Houlihan, Editor, Proceedings of SPIE Vol. 3999(2000), pp. 627-637), and this literature describes a resist including such a SiO2 nanoparticle shows high resolution, and a resist system using a transparent SiO2 nanoparticle is useful to wavelengths such as 157 nm. However, since difference in dissolution rate between exposed area and non-exposed area cannot be enlarged by this method, resolution of a resist cannot be sufficiently improved.
Accordingly, it is an object of the present invention to provide a photoactive compound that is helpful for improving sensitivity and resolution of a resist, concerning the combination with a photosensitizer; a photosensitive resin composition using the photoactive compound; and a process for forming a pattern using the photosensitive resin composition.
It is another object of the present invention to provide a photoactive compound which has high sensitivity even to short wavelength beams emitted from an exposure light source and which is useful for forming a minute pattern with high resolution, a photosensitive resin composition using the photoactive compound, and a process for forming a pattern using the photosensitive resin composition.
It is still another object of the present invention to provide a photoactive compound which is useful for enlarging difference in dissolution rate between exposed area and non-exposed area to a developer, a photosensitive resin composition using the photoactive compound, and a process for forming a pattern using the photosensitive resin composition.